[RICK LAKE]

BMK Bernie It's a combo thing. Lets start with a biggie, FI system of carb?
Next we neex to look at the gear ratios of the trans and rear rear ratio. Tires with cost you about 1-2 mpg if they are real sticky to the road. Street tires with a wear of better that 200 will extend mph.
We don't have any spec on this motor. The big thing again is camshaft and LSA number. The last is the exhaust system, having at cruise speed about 2-4 psi of pressure will give the best mpgs.
Installing a torque( low rpm) cam will give you better mpg. your mileage can be from 10 to 22-25 mpg. It's how you want the car setup. If you go carbs, get to matching ones and setup one for cruising and the other for racing.
The last thing would be to install and A/F meter and watch this. Vacuum gauge will show you how to lite foot driving the car too. Fuel injection will give you a better drivability that carb for every day driving. Carb will get more power from the motor in the higher HP range of the motor.
Hydro roller cam is fine, look for a small one if you are going for MPG. 240-260 duration with the size of the motor. This motor will eat a little larger cam than the stock ones. My 482 has a small roller of 587-607. This is a good size for a 390-428 motor. The extra cubics have this running smooth with just a little idle noise and I mean little. My cam is also retarted 6 degrees for more bottom end power. The cam came with a 4 degree advance built in. I do have too much torque in the bottom end and will advance the cam in the spring. Specs on the motor will help. In see no problems with getting 17-20 mpg with a little work. Rick L.